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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017
♦ If the refrigerant is contaminated, e.g. with chlorine com‐
pounds or by the influence of UV light, metals and also plastics
developed and tested for this refrigerant and refrigerant oil can
be corroded. This can lead to blockages, leaks and deposits
on the air conditioner compressor piston.
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♦ Certain metals can be corroded by R1234yf refrigerant (e.g.
finely distributed aluminium, zinc, magnesium)
6.2.11
Critical temperature / critical pressure of
R1234yf refrigerant
Up to a gas pressure of 32.82 bar (which is equivalent to a tem‐
perature of 94.7°C), refrigerant evaporates at the surface in a
quantity that, combined with particles of vapour, returns it to liquid
again. Above this temperature / pressure there is no longer a sur‐
face separating the liquid and gas.
6.2.12
Water content of R1234yf refrigerant
♦ Only very small amounts of water are soluble in liquid refrig‐
erant. On the other hand, refrigerant vapour and water vapour
mix in any ratio.
♦ Any water in the refrigerant circuit will be entrained in droplet
form once the dryer in the receiver or reservoir is full (once it
has absorbed approx. 7 g of water). This water flows as far as
the expansion valve nozzle or the restrictor and turns to ice.
The air conditioner no longer provides cooling.
♦ If the existing water at the regulating valve of the air conditioner
compressor turns to ice, a variety of complaints may be made
depending on the design of the air conditioner compressor
(either the air conditioning system stops cooling or the air con‐
ditioning system cools to such a degree that the evaporator
ices over).
♦ Water destroys the air conditioner because at high pressures
and temperatures it can combine with other impurities to form
acids.
6.2.13
Flammability / decomposition of
R1234yf refrigerant
♦ In certain concentrations in the ambient air, R1234yf refriger‐
ant is flammable.
♦ R1234yf begins to decompose when exposed to flames and
glowing or hot surfaces. Even UV light causes refrigerant to
break up (UV light is part of normal sunlight, it is also encoun‐
tered e.g. during electrical welding), which releases poisonous
fission products that must not be inhaled. However, these
chemicals irritate the mucous membranes, giving adequate
warning of their presence.
♦ During decomposition, certain hazardous products such as
carbon monoxide, hydrogen fluoride and / or hydrogen halide
can be released.
6.2.14
Charge factor of refrigerant R1234yf
♦ When charging compressed gas containers (returnable cylin‐
ders, recycling cylinders etc.), observe the applicable regula‐
tions, technical rules and legislation.
♦ Never overcharge compressed gas containers (returnable cyl‐
inders, recycling cylinders etc.). The gas cushion (expansion
space) of overcharged compressed gas containers is too
small to accommodate expansion of the fluid caused by a rise
in temperature. Risk of bursting.
6. Basic technical and physical properties
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